Refrigerant recovery device and refrigerant recovery method by use of the same

ABSTRACT

There are provided a compact and portable refrigerant recovery device which can easily recover a refrigerant present in a refrigeration circuit of a used-up household refrigerator or an extra-low temperature freezer which uses a low boiling point refrigerant at low costs, and a method for recovering a refrigerant by using the refrigerant recovery device. In the refrigerant recovery device comprising a refrigerant recovery tank which stores an activated carbon for adsorbing the refrigerant, the recovery tank is equipped with a detachable cap, and the activated carbon is wrapped in unwoven cloth finer than a grain diameter of the activated carbon, and stored in the recovery tank. The refrigerant recovery device is connected to the refrigeration circuit, a gas in the refrigerant recovery tank is vacuumed to be discharged before the refrigerant of the refrigeration circuit is recovered, and then the refrigerant is adsorbed on the activated carbon to be recovered.

BACKGROUND OF THE INVENTION

[0001] The present invention relates to a refrigerant recovery device,and a refrigerant recovery method by use of the same.

[0002] As refrigerants used for a refrigeration unit such as arefrigerator, there have conventionally been availabledichlorodifluoromethane (R-12) and R-500 constituted of R-12 of anazeotropic mixed refrigerant and 1,1-difluoroethane (R-152a) which havethe dangers of destroying an ozone layer.

[0003] As an alternative refrigerant in which a content of a chlorinegroup having a small danger of destroying the ozone layer but having ahigh global warming effect is reduced, for example, there ischlorodifluoromethane (HCFC-22). As refrigerants which contain nochlorine groups, for example, there are difluoromethane (HFC-32, R-32),trifluoromethane (HFC-23, R-23), pentafluoroethane (HFC-125, R-125),1,1,1,2-tetrefluoroethane (HFC-134a, R-134a), 1,1,1-trifluoroethane(HFC-143a, R-143a). There is a fluorocarbon-based refrigerant (FC-basedrefrigerant) which contains neither chlorine groups nor hydrogen, or amixture thereof. Additionally, there are combustible hydrocarbons suchas propane, butane and penta, helium, ammonia, and air.

[0004] When a need arises to recover the refrigerant from arefrigeration circuit because a household refrigerator, an airconditioner or an industrial refrigerator which uses one of theaforementioned refrigerants has been used up, a method is employed,which sucks the refrigerant by using a refrigerant recovery machine toplace it outside the refrigeration circuit, and liquefies therefrigerant to feed it into a cylinder. Alternatively, a method isemployed which runs the refrigerator or the like to liquefy therefrigerants in the refrigeration circuit (pump-down running), sucks theliquefied refrigerants by using the refrigerant recovery machine afterall the refrigerants are liquefied to place them outside therefrigeration circuit, and then feeds the refrigerants into thecylinder.

[0005] The former method is convenient when many used-up householdrefrigerators or the like are collected at the place of the refrigerantrecovery machine to be processed. However, in the case of arefrigeration unit such as a refrigerator located in a faraway region,and an industrial refrigerator, especially an equipment such as amedical equipment in which a special refrigerant is sealed, collectionitself is difficult. Transportation of a large and heavy refrigerantrecovery machine to a far place is very hard, much time and labor arenecessary, and costs are increased. Additionally, there is a problem ofimpossible recovery of a gas refrigerant for an extra-low temperaturefreezer by the recovery machine.

[0006] In the latter case, there are no problems as long as all therefrigerants can be liquefied by the pump-down running. However, ifrefrigerants are low boiling point gas refrigerants or mixtures of lowboiling point gas refrigerants and liquefied refrigerants which haveboiling points higher than those of the gas refrigerants, there is aproblem of impossible recovery because not all the refrigerants can beliquefied or the refrigerants can be liquefied only partially.

[0007] In order to solve the above problems, there have been presented arefrigerant recovery device comprising a refrigerant recovery main body,in which a solid adsorbent to adsorb a refrigerant is stored in acontainer, and a refrigerant recovery method using the device (e.g., seeJapanese Patent Application Laid-Open No. 2000-65447).

[0008] However, if an activated carbon is used for the solid adsorbent,the activated carbon is difficult to be handled because it is finelypowdered or granulated, storage of the activated carbon in the containerand replacement thereof are difficult, measurement takes time and labor,and there is a problem of a scattered loss of the activated carbonoutside the container. When the refrigerant recovery device is connectedto the refrigeration circuit, and a gas in a refrigerant recovery tankis vacuumed to be discharged before the refrigerant of the refrigerationcircuit is recovered, there is a problem that fine grains of theactivated carbon are discharged from the container, and sucked into avacuum pump.

SUMMARY OF THE INVENTION

[0009] A first object of the present invention is to provide a compactand potable refrigerant recovery device which can easily store anactivated carbon in a container and replace the activated carbon withgood handleability of the activated carbon but without any problem of ascattered loss of the activated carbon outside, and which can recover arefrigerant at low costs without any problem of sucking into a vacuumpump when a gas in a refrigerant recovery tank is vacuumed to bedischarged.

[0010] A second object of the present invention is to provide a methodfor easily recovering a refrigerant from a refrigeration circuit of arefrigeration unit at low costs by using the refrigerant recoverydevice.

[0011] That is to say, to solve the above problems, a first aspect ofthe present invention is directed to a refrigerant recovery devicecomprising a refrigerant recovery tank which stores an activated carbonfor adsorbing a refrigerant, wherein the recovery tank is equipped witha detachable cap, and the activated carbon is wrapped in unwoven clothfiner than a grain diameter of the activated carbon, and stored in therecovery tank.

[0012] Since the activated carbon is wrapped in unwoven cloth finer thana grain diameter of the activated carbon, and stored in the recoverytank, handleability is improved, and a problem of a scattered loss tothe outside is eliminated. A cap detachably attached to the recoverytank is opened/closed to enable handling of the activated carbon in itswrapped state in the unwoven cloth, and storage and replacement of theactivated carbon can be easily carried out. Additionally, since theactivated carbon is wrapped in the unwoven cloth finer than the graindiameter of the activated carbon, and stored in the recovery tank, thereis no problem of sucking into the vacuum pump when the gas in therefrigerant recovery tank is vacuumed to be discharged, the refrigerantcan be recovered at low costs, and the device can be made compact andportable.

[0013] A second aspect of the present invention is directed to arefrigerant recovery method comprising a step of connecting therefrigerant recovery device of claim 1 to a refrigeration circuit, and astep of vacuuming a gas in a refrigerant recovery tank to discharge thegas before a refrigerant of the refrigeration circuit is recovered.

[0014] The refrigerant can be efficiently recovered if the refrigerantof the refrigeration circuit is recovered after the gas in therefrigerant recovery tank is vacuumed.

[0015] A third aspect of the present invention is directed to therefrigerant recovery method, wherein a filter of unwoven cloth finerthan a grain diameter of an activated carbon is arranged on a path ofthe vacuuming.

[0016] By arranging the filter of the unwoven cloth finer than the graindiameter of the activated carbon on the path of the vacuuming, theactivated carbon is captured by the filter even if the activated carbonis leaked from the refrigerant recovery tank during vacuuming. Thus, itis possible to prevent sucking into the vacuum pump.

[0017] A fourth aspect of the present invention is directed to therefrigerant recovery method, wherein a refrigerant is a low boilingpoint gas refrigerant or a mixture of a low boiling point gasrefrigerant and a liquefied refrigerant which has a boiling point higherthan that of the gas refrigerant.

[0018] Even in the case of the low boiling point gas refrigerant whichcannot be liquefied by pump-down running, or the mixture of the lowboiling point gas refrigerant and the liquefied refrigerant which hasthe boiling point higher than that of the gas refrigerant, therefrigerant can be recovered by adsorbing it on the activated carbon inthe refrigerant recovery tank.

BRIEF DESCRIPTION OF THE DRAWINGS

[0019]FIG. 1 is a view illustrating a state in which a refrigerantrecovery device of the present invention is connected to a refrigerationcircuit of a refrigerator or the like.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020] Next, the preferred embodiment of the present invention will bedescribed with reference to the accompanying drawing.

[0021] In FIG. 1, a reference numeral 1 denotes a refrigeration circuitof a refrigerator or the like on which a compressor 2 is mounted. Thecompressor 2 is sequentially connected to a condenser 3, a capillarytube 4 and an evaporator 5 to constitute a refrigeration circuit. Arefrigerant recovery device 6 of the present invention is connected tothe compressor 2 in the refrigeration circuit.

[0022] The refrigerant recovery device 6 comprises a duct 7 forconnection to the refrigeration circuit, an opening/closing valve 8disposed on the duct 7, a refrigerant recovery tank 10 which stores anactivated carbon 9 to adsorb a refrigerant of the refrigeration circuit1, etc. One end of the duct 7 is connected to a tip of a sealing-in pipe11 for sealing a refrigerant in the compressor 2 of the refrigerationcircuit 1. A reference numeral 12 denotes a pressure gauge.

[0023] The refrigerant recovery tank 10 is equipped with a detachablecap 13. The activated carbon 9 is wrapped in unwoven cloth 14 finer thana grain diameter of the activated carbon 9, and stored in therefrigerant recovery tank 10. A reference numeral 15 denotes a bolt/nutwhich detachably fixes the cap 13 to the refrigerant recovery tank 10.The activated carbon 9 wrapped in the unwoven cloth 14 is stored in therefrigerant tank 10, and then fixed by using the bolt/nut 15. In thecase of replacing the activated carbon wrapped in the unwoven cloth 14or the like, the bolt/nut 15 is removed to open the cap 13, whereby theactivated carbon 9 can be integrally taken out from the refrigerantrecovery tank 10.

[0024] A reference numeral 16 denotes a vacuuming line set in the cap13, and 17 an opening/closing valve disposed in the vacuuming line 16. Areference numeral 18 denotes a filter which comprises unwoven clothfiner than a grain diameter of the activated carbon. When vacuuming iscarried out in the refrigerant recovery tank 10, it is carried out byclosing the opening/closing valve 8, opening the opening/closing valve17 to connect the vacuuming line 16 to a not-shown vacuum pump, andactuating the vacuum pump.

[0025] By arranging the filter 18 in the vacuuming line 16, fine grainsare captured by the filter even if the fine grains of the activatedcarbon are leaked from the refrigerant recovery tank 10 duringvacuuming.

[0026] The refrigerant recovery device 6 is simple in constitution,compact and portable, easily transported and installed, and handling andan operation are easy.

[0027] According to the aforementioned constitution, when a need arisesto recover the refrigerant in the refrigeration circuit because therefrigerator 1 has been used up or the like, the opening/closing valve 8is opened, and the refrigerant flows in a direction indicated by anarrow to be adsorbed on the activated carbon 9 without using a suctionpump or the like. Thus, it is possible to recover substantially all therefrigerants of the refrigeration circuit in the refrigerant recoverytank 10.

[0028] Vacuuming is executed beforehand in the refrigerant recovery tank10, and the opening/closing valve 8 is opened during recovery. Thus, itis possible to more efficiently recover the refrigerant of therefrigeration circuit in the refrigeration recovery tank 10. That is,the opening/closing valve 8 is fired closed, and the opening/closingvalve 17 is opened to connect the vacuuming line 16 to the not-shownvacuum pump. The vacuum pup is actuated to execute vacuuming, andvacuuming is carried out beforehand in the refrigerant recovery tank 10.When the refrigerant of the refrigeration circuit is recovered, theopening/closing valve 17 is closed, and the opening/closing valve 8 isopened, whereby the refrigerant can be adsorbed on the activated carbon9 to be recovered.

[0029] The activated carbon used by the present invention is selectedfrom activated carbons of powdered, granulated, fiber and molded shapes.The activated carbon used by the invention is made of a carbonaceous rawmaterial such as a coconut husk, a coal, an oil-based pitch, or an oilcarbon. Preferably, a specific surface area is 400 m²/g or higher by aBET method, more preferably 1000 m²/g or higher.

[0030] The amount of the activated carbon used by the invention isproperly decided based on the amount of the refrigerant in therefrigeration circuit.

[0031] The unwoven cloth used by the invention is finer than a graindiameter of the activated carbon. A material may be, e.g., plastic, acarbon fiber, a natural fiber, a metal fiber, a glass fiber or a ceramicfiber as long as the wrapped activated carbon is not put out from thetexture of the unwoven cloth when the activated carbon is wrapped, butthe refrigerant is passed through the texture and adsorbed on theactivated carbon to be recovered, the activated carbon can be integrallyhandled in the wrapped state in the unwoven cloth, and storage andreplacement of the activated carbon can be integrally carried outeasily. There are no particular limitations on shapes and types. Aporous film, a porous sheet, a bag, or various container types to bestored in the refrigerant recovery tank may be used.

[0032] Next, the present invention will be described more in detail byway of examples. Apparently, widely different examples can beconstituted without departing from the spirit and scope of theinvention. Thus, the specific examples are not limitative of theinvention which is only is limited by the appended claims.

EXAMPLE 1

[0033] A test was conducted to recover a refrigerant by connecting therefrigerant recovery device of the present invention to a binaryrefrigeration circuit in which two refrigeration circuits shown in FIG.1 were used. Refrigerant: high-temperature side; R407D [difluoromethane,pentafluoroethane, 1,1,1,2-tetrafluoroethane]+6 pt, low-temperatureside; R508 [trifluoromethane/hexafluoromethane mixed refrigerant]

[0034] Refrigerant charge amount: 205 g on the low-temperature side

[0035] Refrigerant recovery tank capacity: about 2.5 liters

[0036] Activated carbon: granular activated carbon using coconut husk inthe form of pellets of 8 to 10 mesh and grain diameter 1.70 to 2.00 mmas a main raw material, the amount of use: 930 g, and the activatedcarbon, when used, was wrapped in unwoven cloth as shown in FIG. 1.

[0037] The refrigerant of the high-temperature side was recovered by aconventional method which used a recovery machine.

[0038] In the case of recovery of the refrigerant of the low-temperatureside, the opening/closing valve 8 was first closed, the opening/closingvalve 17 was opened to connect the vacuuming line 16 to the not shownvacuum pump, the vacuum pimp was actuated to execute vacuuming, andvacuuming was executed beforehand (3.6 Pa) in the refrigerant recoverytank 10. When the refrigerant was recovered, the opening/closing valve17 was closed, the opening/closing valve 8 was opened, and the amount ofthe recovered refrigerant adsorbed on the activated carbon with theelapse of time, and pressure indicated by the pressure gauge 12 weremeasured.

[0039] The following shows results of the measurement. Amount of Elapsedrecovered time refrigerant Pressure (min.) (g) (MPaG) 0.5 — 0.02 5 171−0.01 12 171 −0.01

[0040] Thus, a recovery rate of 83.4% was obtained in about 5 min. Ifthe refrigerant can be recovered up to about pressure of −0.01 MPaG, noresidual refrigerant is discharged from the refrigeration circuit intothe atmosphere. The residual refrigerant may conceivably be dissolved inrefrigerator oil.

EXAMPLE 2

[0041] A test was conducted to recover a refrigerant under the followingconditions as in the case of Example 1.

[0042] Refrigerant: R21 [dichlorofluoromethane], R22[chlorodifluoromethane], R14 [tetrafluoromethane], R508[trifuoromethane/hexafluoromethane mixed refrigerant]

[0043] Refrigerant charge amount: 463 g

[0044] Refrigerant recovery tank capacity: about 5 liters

[0045] Activated carbon: granular activated carbon using coconut husk inthe form of pellets of 8 to 10 mesh and grain diameter 1.70 to 2.00 mmas a main raw material, the amount of use: 2020 g, and the activatedcarbon, when used, was wrapped in unwoven cloth as shown in FIG. 1.

[0046] The following shows results of measurement. Amount of Elapsedrecovered time refrigerant Pressure (min.) (g) (MPaG) 5 — 0.02 10 3200.01 21 325 −0.03

[0047] For the recovery of the refrigerant, the opening/closing valve 8was first closed, the opening/closing valve 17 was opened to connect thevacuuming line 16 to the not-shown vacuum pump, the vacuum pimp wasactuated to execute vacuuming, and vacuuming was executed beforehand(3.6 Pa) in the refrigerant recovery tank 10. When the refrigerant wasrecovered, the opening/closing valve 17 was closed, the opening/closingvalve 8 was opened, and the amount of the recovered refrigerant adsorbedon the activated carbon with the elapse of time, and pressure indicatedby the pressure gauge 12 were measured.

[0048] Thus, a recovery rate of 69.1% was obtained in about 10 min. Ifthe refrigerant can be recovered up to about pressure of −0.01 MPa, noresidual refrigerant is discharged from the refrigeration circuit intothe atmosphere. The residual refrigerant, especially high boiling pointR21 and R22, may conceivably be dissolved in refrigerator oil. Thus, byprocessing the refrigerator oil, the residual refrigerant can beprocessed.

EXAMPLE 3

[0049] A test was conducted to recover a refrigerant under the followingconditions by using a large charge amount large-size machine at a binaryrefrigeration circuit as in the case of Example 1.

[0050] Refrigerant: high-temperature side; R412A [chlorodifluoromethane,octafluoropropane, 1-chloro-1,1-difluoroethane], low-temperature side;R508 [trifluoromethane, hexafluoromethane mixed refrigerant]

[0051] Refrigerant charge amount: 345 g

[0052] Refrigerant recovery tank capacity: about 5 liters

[0053] Test temperature: 26° C.

[0054] Activated carbon: granular activated carbon using coconut husk inthe form of pellets of 8 to 10 mesh and grain diameter 1.70 to 2.00 mmas a main raw material, the amount of use: 2020 g, and the activatedcarbon, when used, was wrapped in unwoven cloth as shown in FIG. 1.

[0055] The refrigerant of the high-temperature side was recovered by aconventional method which used a recovery machine.

[0056] In the case of recovery of the refrigerant of the low-temperatureside, the opening/closing valve 8 was first closed, the opening/closingvalve 17 was opened to connect the vacuuming line 16 to the not-shownvacuum pump, the vacuum pimp was actuated to execute vacuuming, andvacuuming was executed beforehand (3.6 Pa) in the refrigerant recoverytank 10. When the refrigerant was recovered, the opening/closing valve17 was closed, the opening/closing valve 8 was opened, and the amount ofthe recovered refrigerant adsorbed on the activated carbon with theelapse of time to be recovered, and pressure indicated by the pressuregauge 12 were measured.

[0057] The following shows results of the measurement. Amount of elapserecovered of time refrigerant Pressure (min.) (g) (MPaG) 10 — −0.02 15310 −0.02

[0058] Thus, a recovery rate of 89.9% was obtained in about 15 min. Ifthe refrigerant can be recovered up to about pressure of −0.01 MPa, noresidual refrigerant is discharged from the refrigeration circuit intothe atmosphere. The residual refrigerant may conceivably be dissolved inrefrigerator oil.

[0059] The examples of recovering the low boiling point refrigerantssuch as R508 have been described. However, the present invention is notlimited to the examples. For example, high boiling point refrigerantscan be recovered.

[0060] The present invention provides the following marked effects. Thatis, the refrigerant recovery device comprising the refrigerant recoverytank which stores the activated carbon for adsorbing the refrigerant ischaracterized in that the recovery tank is equipped with the detachablecap, and the activated carbon is wrapped in the unwoven cloth finer thana grain diameter of the activated carbon, and stored in the recoverytank. Since the activated carbon is wrapped in the unwoven cloth finerthan the grain diameter of the activated carbon, and stored in therecovery tank, handleability is improved, and a problem of a scatteredloss to the outside is eliminated. The cap detachably attached to therecovery tank is opened/closed to enable handling of the activatedcarbon in its wrapped state in the unwoven cloth, and storage andreplacement of the activated carbon can be easily carried out.Additionally, since the activated carbon is wrapped in the unwoven clothfiner than the grain diameter of the activated carbon, and stored in therecovery tank, there is no problem of sucking into the vacuum pump whenthe gas in the refrigerant recovery tank is vacuumed to be discharged,the refrigerant can be recovered at low costs, and the device can bemade compact and portable.

[0061] The present invention provides the following marked effect. Thatis, the refrigerant recovery method is characterized by comprising:connecting the refrigerant recovery device to the refrigeration circuit;and vacuuming a gas in the refrigerant recovery tank to discharge thegas before the refrigerant of the refrigeration circuit is recovered.The refrigerant can be efficiently recovered if the refrigerant of therefrigeration circuit is recovered after the gas in the refrigerantrecovery tank is vacuumed.

[0062] The present invention provides the following marked effect. Thatis, in the refrigerant recovery method, the filter of the unwoven clothfiner than the grain diameter of the activated carbon is arranged on thepath of the vacuuming. The activated carbon is captured by the filtereven if the activated carbon is leaked from the refrigerant recoverytank during vacuuming. Thus, it is possible to prevent sucking into thevacuum pump.

[0063] Furthermore, the present invention provides the following markedeffect. That is, in the refrigerant recovery method, the refrigerant isthe low boiling point gas refrigerant or the mixture of the low boilingpoint gas refrigerant and the liquefied refrigerant which has a boilingpoint higher than that of the gas refrigerant. Even in the case of thelow boiling point gas refrigerant which cannot be liquefied by pump-downrunning, or the mixture of the low boiling point gas refrigerant and theliquefied refrigerant which has the boiling point higher than that ofthe gas refrigerant, the refrigerant can be recovered by adsorbing it onthe activated carbon in the refrigerant recovery tank.

What is claimed is:
 1. A refrigerant recovery device comprising: arefrigerant recovery tank which stores an activated carbon for adsorbinga refrigerant, wherein the recovery tank is equipped with a detachablecap, and the activated carbon is wrapped in unwoven cloth finer than agrain diameter of the activated carbon, and stored in the recovery tank.2. A refrigerant recovery method comprising: connecting the refrigerantrecovery device of claim 1 to a refrigeration circuit; and vacuuming agas in a refrigerant recovery tank to discharge the gas before arefrigerant of the refrigeration circuit is recovered.
 3. Therefrigerant recovery method according to claim 2, wherein a filter ofunwoven cloth finer than a grain diameter of an activated carbon isarranged on a path of the vacuuming.
 4. The refrigerant recovery methodaccording to claim 2 or 3, wherein a refrigerant is a low boiling pointgas refrigerant or a mixture of a low boiling point gas refrigerant anda liquefied refrigerant which has a boiling point higher than that ofthe gas refrigerant.